1. Field of the Invention
The present invention relates to novel fluoran derivatives, a process for the preparation thereof and a recording material containing the derivatives as a heat-sensitive coloring component.
2. Description of the Related Art
Heat-sensitive recording materials comprising an electron-donative fluoran dye and an electron-receptive compound are well-known (see, for example, Japanese Examined Patent Publication No. 51-23204, Japanese Unexamined Patent Publication No. 57-31591, Japanese Unexamined Patent Publication No. 58-52356 and Japanese Unexamined Patent Publication No. 60-36568). As the fluoran dye, there can be mentioned 3-N,N-diethylamino-7-o-chloroanilinofluoran and 3-(N-methyl-N-cyclo-hexylamino)-6-methyl-7-anilinofluoran as the color former.
The properties that should be at least possessed by such recording materials are as follows.
(1) The coloration density and coloration sensitivity are sufficient.
(2) Fogging is not caused.
(3) The colored body after the color development has a sufficient fastness.
However, recording materials capable of satisfying all of these requirements sufficiently have not been developed.
A heat-sensitive recording paper comprising a known fluoran dye as mentioned above is defective in that when a plasticizer, an oil or an organic solvent falls in contact with a colored portion, the color comes off.